In the related art, as this type of electric opening and closing device, there is proposed a device provided with a torque limiter having an outer ring integrally rotating with a worm, a sleeve integrally rotating with a motor shaft, and an inner ring provided on an outer circumference of the sleeve so as to be relatively non-rotatable, and a coil spring that is engaged with the outer ring, fastened to the inner ring, and generates relative rotation between the outer ring and the inner ring in a case where an external force equal to or greater than a predetermined load is applied thereto (for example, refer to JP 2010-246880A (Reference 1)). The electric opening and closing device decelerates rotation of the worm and opens and closes a driven member (toilet seat and toilet lid) by a reduction gear mechanism having a worm wheel meshed with the worm.
In the above-described electric opening and closing device, since the outer ring, the sleeve, and the inner ring are required in addition to the coil spring, the device is complicated. In addition, in the above-described electric opening and closing device, although the torque limiter is provided between the motor shaft and the worm, but since the worm has a large variation in the torque transmission efficiency, it is difficult to control a slip torque.
Thus, a need exists for an electric opening and closing device which is not susceptible to the drawback mentioned above.